Abstract: A multichannel parallel LD/PD module comprising a bench, a plurality of lightpaths having an initial narrow width region, an intermediate width enlarging region and a final wide width region, a plurality of photodiodes or a photodiode array mounted on the narrow width region, a wavelength selective filter formed on the narrow width region for selectively reflecting receiving beams, a plurality of light emitting devices fitted behind rear ends of the lightpaths on the bench. Traveling in element fibers in an outer ribbon fiber, receiving signal beams go into the lightpaths via front ends and are reflected by the wavelength selective filter slantingly upward at the narrow width region. The reflected beams go into the photodiodes and are converted into photocurrents in proportion to the receiving signals.

Abstract: A photodiode having a resin film painted upon an opening through which signal light goes in and a dielectric multilayered film piled upon the resin film for reflecting noise light. The elasticity of the resin film prevents the dielectric multilayered film from transforming or exfoliating by alleviating inner stress due to piling of tens to hundreds of different rigid dielectric layers.

Abstract: An optical transceiver module is comprised of a mount substrate, a transmitting semiconductor laser, a receiving photodiode, a communicating hole, and a first filter. The mount substrate is provided so as to intersect with a predetermined axis X and has first and second principal surfaces facing each other. The transmitting semiconductor laser is mounted on the first principal surface and is configured to emit light of a first wavelength. The receiving photodiode is mounted on the predetermined axis X and on the second principal surface and is configured to receive light of a second wavelength. The communicating hole is provided in a region of the mount substrate where the receiving photodiode is mounted, and makes the first and second principal surfaces communicate with each other. The first filter is provided on the predetermined axis X and in a region intersecting with the first principal surface and is configured to reflect the light of the first wavelength and transmit the light of the second wavelength.

Abstract: An optical transceiver module comprises a submodule having a Y-branching optical transmission line formed on a flat platform such that a leading end is exposed at the front surface and having an LD chip and a PD chip disposed at first and second trailing ends of the optical waveguide. The submodule is secured to the front surface of a pole of a metal stem, and a condenser lens and an end of an optical fiber are secured relative to the stem by a metal package member so that the optical fiber and the leading end of an optical waveguide can be optically coupled by the condenser lens. Transmission light from the LD is focused by the lens and can be sent out to the optical fiber, and reception light that has propagated through the optical fiber can be received by the PD. Thus, the optical transceiver module whose submodule is accommodated in a metal package is superior in reliability, durability, and airtightness.

Abstract: An optical transmission module is constructed in a configuration wherein a semiconductor laser is mounted on a stem-side emitter loading portion of a pole provided on a stem and wherein light emitted forward from the semiconductor laser is outputted through a condenser lens and others. A monitor photodiode is mounted on a receiver loading portion of the pole on the forward side of the semiconductor laser and the photodiode detects part of the light emitted forward from the semiconductor laser, to monitor the operating condition of the semiconductor laser. This configuration achieves decrease in the length of a lead pin and thus restrains deterioration of the waveform of the drive current to the semiconductor laser.

Abstract: An optical communication device having an optical fiber, other optical parts, a transparent potting resin with a refractive index akin to the fiber and a pressurizing element with extra pressure in contact with the potting resin for applying positive pressure upon the potting resin with a predetermined temperature range. The present optical communication device can solve the problems of decline of sensitivity of PDs and instability of the oscillation of LDs in a low temperature region between −40° C. and 0° C. after a heat cycle test.

Abstract: A producing method an optical module is carried out as shown below. First, an optical-communication functional portion is disposed on a lead frame where each lead is held by an insulating connection leads. A screening test for the optical communication functional portion is performed. A product selected through a screening test process is packaged. In the above-mentioned method, the connection leads which are electrically insulated with one another and the screening test is performed before packaging or encapsulating. Consequently, the waste accompanied by discarding the component elements of the optical module, which has caused an increase in the cost, can be eliminated. Further, an attempt to reduce the cost of products can also be made.

Abstract: Besides the central pn-junction and the central electrode, a PD chip has a peripheral pn-junction and a peripheral electrode which do not appear on the sides. The ends of the peripheral pn-junction are covered with a protection layer for preventing self-shortcircuit. A reverse bias is applied to the peripheral electrode for making a wide depletion layer beneath the peripheral pn-junction. Extra carriers generated by peripherally-incidence rays are fully absorbed by the peripheral depletion layer and annihilated by the reverse bias.

Abstract: An optical receiver comprises (a) an optical fiber, (b) a rear-illuminated type PD for receiving incoming light emerging from the optical fiber, (c) a submount supporting the PD, (d) a coaxial type package housing the submount, and (e) a preamplifier IC for amplifying electric signals from the PD. In particular, the submount is provided with a reflecting face for reflecting the incoming light so that the light can enter the PD. The submount may be provided with an optical path-forming groove having at least one reflecting face for introducing and reflecting the incoming light so that the light can enter the light-receiving portion of the PD mounted on the submount. This structure enables the production of an optical receiver most suitable for high-speed response and excellent in productivity. A method of producing the optical receiver is also offered.

Abstract: An optical module comprising a column-shaped mounting member having a through hole extending along the central axis thereof and having a mounting surface formed by incising a part of the mounting member so as to expose the interior surface of the through hole; and an optical fiber inserted in the through hole and secured in a configuration such that the optical fiber protrudes with a specified length onto the mounting surface. The structure, in which a Bragg diffraction grating is formed in such protruding part of the optical fiber on said mounting surface, can prevent the occurrence of a change in reflective characteristic of the Bragg diffraction grating.

Abstract: A photodiode that is used in an optical communication system using two different wavelengths, &lgr;1 and &lgr;2 (&lgr;1<&lgr;2), and that enables a reduction in the optical crosstalk caused by outgoing light having a longer wavelengths, &lgr;2. A photodiode that receives light having a shorter wavelengths, &lgr;1, is provided with an absorption layer made of a material having a bandgap wavelength, &lgr;g. (&lgr;1<&lgr;g<&lgr;2), to detect the light having &lgr;1. A filter layer that absorbs unwanted light having &lgr;2 is provided over the absorption layer so that the light having &lgr;2 cannot return to the absorption layer after passing through it once.

Abstract: A light emitting device has a fiber stub component, a grating chip, a semiconductor optical amplifier, a photodiode, and a mount member. The fiber stub component is comprised of a ferrule and an optical fiber. The fiber stub component, grating chip, and semiconductor optical amplifier are mounted on the mount member and are optically coupled to each other. An optical cavity is comprised of a light reflecting surface of the semiconductor optical amplifier and a diffraction grating of the grating chip. In this configuration, the light emitting device can provide laser light of a desired wavelength, without use of a pigtail fiber. The light emitting device can be constructed in smaller size than those using the pigtail fiber.

Abstract: The optical communication module comprises a laminated lead frame composed of a plurality of lead frames that are laminated and held by a tie bar made of an insulating material, and an optical communication functional unit that is disposed on at least one layer of the lead frame. The optical communication functional unit comprises at least one of a light emitting element (LD) and a light receiving element and an optical transmission medium (optical fiber).

Abstract: An optical transmitter comprises an optical transmission unit having a semiconductor optical amplifier, and an optical connector having a plurality of diffraction gratings. The plurality of diffraction gratings are arranged in parallel with each other and partly reflect respective wavelengths of light different from each other. The optical connector is connected to the optical transmission unit such that light from the semiconductor optical amplifier is incident on one of the plurality of diffraction gratings.

Abstract: In optical module 1a, substrate 3 has first and second regions 3a, 3b and first and second optical waveguides 3c, 3d. First and second regions 3d, 3e are arranged along a predetermined plane. First and second optical waveguides 3d, 3e are provided in the first region 3a and extend in a direction of a predetermined axis. Semiconductor light emitting device 7 includes a semiconductor light emitting element 7a optically coupled to first optical waveguide 3c and provided in second region 3e. Semiconductor driving element 9 is electrically connected to semiconductor light emitting element 7a. Semiconductor driving element 9 is mounted on mount member 13. Light receiving element 15a reflects a part of incident light and transmits a part of the incident light, and semiconductor light receiving device 17 includes a light receiving element 17a provided in first region 3a so as to be optically coupled to optical element 15a.

Abstract: The present invention relates to a high-sensitivity top-electrode and bottom-illuminated type photodiode. The device consists of a highly doped buffer layer, a photo-detecting layer on a semi-insulating substrate. An electrode is formed on the conductive domain that is formed in the photo-detecting layer, and another electrode is formed on the partly exposed peripheral area of the highly-doped buffer layer by removing a part of the photo-detecting layer. As the semi-insulating substrate absorbs less light in the substrate, a decrease of sensitivity by the substrate absorption can be prevented.

Abstract: A photodiode (PD chip) includes a substrate, an absorption layer, a p-n junction in the absorption layer, a passivation film for protecting the end of the p-n junction, a p-electrode, and an n-electrode. The passivation film is covered with a protective layer composed of an insulative resin and having a thickness larger than that of the passivation film such that the passivation film of the PD chip fixed to the Si wafer and hence the p-n junction are not damaged or contaminated when an Si wafer including a number of horizontally and vertically arranged chip units, each having a V-groove for fixing an optical fiber, a marker, and a metallized pattern, is diced. Thus, a low-cost optical receiver module that does not generate dark current can be produced.

Abstract: An optical receiver comprises a PD for receiving an incident light from an optical fiber, a preamplifier IC for amplifying an electrical signal from the PD, a submount on which the PD and the preamplifier IC are mounted on the same plane, and a package on which the submount is mounted. The PD and the preamplifier IC are directly connected to each other by a wire, and these components are both mounted on the same submount. Therefore, the distance between the PD and the preamplifier IC can be reduced, and parasitic inductance, parasitic capacitance, etc. can be greatly reduced. As a result, an optical receiver is provided which has reduced parasitic inductance and parasitic capacitance, and which is optimum for high speed response.

Abstract: An optical communications module in which electrical crosstalk is reduced. The term “optical communications module” represents a surface-mounting-type optical tranceiver, transmitter, or receiver module. The optical communications module has a following structure. (a) An Si substrate carries at least one signal-transmitting section comprising an LD, at least one signal-receiving section comprising a PD, or both together with other components. (b) An insulating substrate is bonded to the back face of the Si substrate. (c) A separating groove separates the Si substrate along the or each boundary line between the sections in order to prevent an AC current flowing through the Si substrate. To attain this object, the separating groove is provided from the top surface of the Si substrate to some midpoint of the insulating substrate.

Abstract: Standardized multichannel optical fiber has a pitch 250 &mgr;m (P1). Mounting of optoelectronic device chips requires a pitch P2 larger than P1. The pitch of element fibers should be enlarged for coupling a multichannel ribbon fiber to a multichannel PD or LD module having photodiodes or laser diodes of the channel number M. The module includes a connector maintaining M (channel number) fibers with tails extending backward, a bench having M V-grooves aligning at the pitch P2 larger than the pitch P1 for receiving the tails of the fibers, M lightwaveguides aligning at the pitch P2 following the V-grooves and M photodiodes or laser diodes following the lightwaveguides and a package containing the connector at a front part, the fiber tails at a width enlarging region for converging the pitch from P1 to P2 and the bench at a back part.